Hybrid contact lens system and method

ABSTRACT

A hybrid hard-soft contact lens is provided. Several embodiments of the invention include methods of coupling the hard and soft sections of the contact lens. Other embodiments of the invention include contact lens materials and coatings that increase oxygen transmission though the lens. Yet other embodiments of the invention are directed to cost-effective manufacturing methods of a hybrid hard-soft contact lens. This Abstract is provided for the sole purpose of complying with the Abstract requirement rules that allow a reader to quickly ascertain the subject matter of the disclosure contained herein. This Abstract is submitted with the explicit understanding that it will not be used to interpret or to limit the scope or the meaning of the claims.

Priority is claimed to U.S. Provisional Application Ser. No. 60/408,618,filed Sep. 6, 2002, titled “Hybrid Contact Lens System and Method,”which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention generally relates to contact lenses. Moreparticularly, the invention concerns a hybrid hard-soft contact lens.

BACKGROUND OF THE INVENTION

Vision correction is on the verge of a revolution. New technologies tomeasure the aberrations or distortions in the optics of the eye willsoon be available to the public. These new wavefront measurementtechniques such as Shack-Hartmann wavefront sensing or TalbotInterferometry can precisely measure the eye's aberrations so thatvision may be corrected up to 20/10. Wavefront sensing is the method forrapidly, and very accurately, assessing the aberrations in anindividual's eye to create a customized prescription for correction.

However, once the eye's aberrations have been measured, either byconventional methods or by wavefront sensing, these measurements mustthen be transferred into a vision correction system, such as eyesurgery, spectacles, or contact lenses. Recent advances in laserrefractive surgery techniques such as LASIK and photorefractivekeratectomy, as well as improvements in spectacle lens manufacturing nowenable the creation of highly accurate corrective prescriptions forindividuals.

However, this is not the case with contact lenses. Popular soft contactlenses cannot achieve the same result as spectacles or laser refractivesurgery because of dimensional variations in fabrication. Hard contactlenses, which may provide the platform to achieve the results ofspectacles, are not as comfortable as soft contacts and lack thenecessary positional stability on the eye.

Therefore, there exists a need for a hybrid hard-soft contact lens thatcan provide a platform for a corrective prescription and also providethe comfort of soft contact lenses.

SUMMARY OF THE INVENTION

A hybrid hard-soft contact lens is provided. Several embodiments of theinvention include methods of coupling the hard section of the lens tothe soft section of the lens. Other embodiments of the invention includecontact lens materials that increase oxygen transmission though thelens. Yet other embodiments of the invention are directed tocost-effective manufacturing methods of a hybrid hard-soft contact lens.

These and other features and advantages of the present invention will beappreciated from review of the following detailed description of theinvention, along with the accompanying figures in which like referencenumerals refer to like parts throughout.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a manufacturing step used to construct ahybrid hard-soft contact lens of the present invention;

FIG. 2. is a front view of a contact lens blank after the manufacturingstep illustrated in FIG. 1;

FIG. 3 is a front view of another manufacturing step used to construct ahybrid hard-soft contact lens of the present invention;

FIG. 4 illustrates another manufacturing step used to construct a hybridhard-soft contact lens of the present invention;

FIG. 5 illustrates an alternative manufacturing method of constructing ahybrid hard-soft contact lens of the present invention;

FIG. 6 illustrates several embodiments of interface geometries between ahard section and soft section of a hybrid hard-soft contact lensconstructed according to the present invention;

FIG. 6A illustrates a preferred embodiment of an interface geometrybetween a hard section and soft section of a hybrid hard-soft contactlens constructed according to the present invention;

FIG. 7 is an illustration of a contact lens, several eye components andvisible light rays exiting the eye-contact lens system;

FIG. 8 is another illustration of a contact lens, eye components andvisible light rays, showing the tendency for different colored lightrays to exit the eye at different angles;

FIG. 9 illustrates a hypothetical uniform eye response to the visiblelight spectrum;

FIG. 10 illustrates a photopic eye response to the visible lightspectrum; and

FIG. 11 illustrates one idealized net wavelength response for a contactlens constructed according to the present invention.

It will be recognized that some or all of the Figures are schematicrepresentations for purposes of illustration and do not necessarilydepict the actual relative sizes or locations of the elements shown.

DETAILED DESCRIPTION OF THE INVENTION

In the following paragraphs, the present invention will be described indetail by way of example with reference to the attached drawings.Throughout this description, the preferred embodiment and examples shownshould be considered as exemplars, rather than as limitations on thepresent invention. As used herein, the “present invention” refers to anyone of the embodiments of the invention described herein, and anyequivalents. Furthermore, reference to various feature(s) of the“present invention” throughout this document does not mean that allclaimed embodiments or methods must include the referenced feature(s).

The present invention is based on a hybrid contact lens platform thatoffers the benefits, without the disadvantages, of both soft and gaspermeable contact lenses—comfort, health, stability, superior optics anddurability. The features of the present invention include lenschemistry, manufacturing processes, optical design and prescribing andfitting processes. One feature of the manufacturing processes andoptical design elements is the ability to make quarter wavelengthcustomization in order to correct for the higher order refractiveaberrations that limit one's ability to see better than 20/20.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as is commonly understood by one of skill in theart to which this invention belongs. In event the definition herein isnot consistent with definitions elsewhere, the definitions set forthherein will control. As used herein, “hybrid” refers to a type ofcontact lens that includes both hard and soft lens elements.

One embodiment of the present invention will correct normal ametropicerrors (myopia, hyperopia and astigmatism) to a higher degree of visualperformance than conventional contact lenses. Another embodiment of thepresent invention will correct for the wavefront-guided higher orderaberrations and will create a new contact lens category, providing“super vision” for those whose visual requirements demand better than20/20 acuity. Yet another embodiment of the present invention willcorrect for presbyopia, the gradually increasing inability to focus atclose distances that usually begins after age 40. Other embodiments ofthe present invention may include contact lenses that incorporateseveral, or all of the above-described features.

Another embodiment of the present invention is a hybrid lens thatcombines the optical clarity, stability and durability of a gaspermeable lens with the comfort of a soft contact lens. This hybrid lenshas a gas permeable center chemically bonded to a soft outer skirt. Thecenter is highly oxygen permeable, which is important to maintainingcorneal health. One of the manufacturing processes of the presentinvention enables this gas permeable center to be lathed to quarterwavelength precision, allowing corrections of wavefront-guided higherorder refractive aberrations and providing visual performance betterthan 20/20.

Yet another embodiment hybrid contact lens of the present invention hasa soft outer skirt with a radius of curvature greater than the basecurve of the oxygen permeable center, which is suspended on the softskirt, thus creating a lighter touch above the corneal apex. One featureof this embodiment is that the eyelid force of normal blinking creates aperistaltic-like pump that exchanges the tears under the lens,contributing to overall comfort, and eliminating dryness, the mostfrequent complaint of contact lens wearers. Another feature of thisembodiment is that the tear layer under the lens is not only importantfor comfort and health, but it has optical correction qualities as well.A layer of tears retained behind the base curve of the gas permeablelens of the present invention may correct corneal astigmatism by up toabout ten diopters. Thus, a hybrid contact lens constructed according tothe present invention creates a superior astigmatism correctingcapability that does not rely on orientation and positioning, as do softcontact lenses. Another embodiment of the present invention comprises ahybrid lens with a substantially rigid center that is chemically bondedto a softer outer skirt. One embodiment of the outer skirt is comprisedof a modified HEMA (poly-2-hydroxyethyl-methacrylate) material. Thecenter is a substantially rigid gas permeable-type with a gaspermeability DK value greater than 30. A preferred embodiment centerwould have a gas permeability DK value of about 150. However, otherembodiments may have a gas permeability DK value that may range betweenabout 30 to about 250. In a preferred embodiment of the presentinvention, the substantially rigid center is made from any of thefollowing materials: fluoro-siloxane acrylate, siloxane acrylate, orpoly-styrene siloxane acrylate.

The substantially rigid center section may have a thickness that mayrange between about 0.03 millimeters (mm) to about 0.5 mm., and adiameter that may range between about 4.0 mm. to about 12.0 mm. Theoverall diameter of a hybrid contact lens constructed according to thepresent invention may range between about 10.0 mm. to about 18.0 mm.

The substantially rigid center may have a spherical or ellipsoidalocular (i.e., eye-facing) surface. Unlike soft lenses, the substantiallyrigid center of the present invention contact lens is resistant toprotein deposition. One feature of the present invention contact lens isthat it is also highly resistant to foreign body migration as well asdislodgement from the eye during contact sports, or other vigorousactivities. A contact lens constructed according to the presentinvention also provides excellent centering and vision correction forirregular corneas created by trauma or surgery.

Hybrid Contact Lens Geometry

One embodiment of the present invention comprises a centralsubstantially rigid gas permeable portion having a posterior surfacethat is either spherical, aspherical or toroidal, which is chosen toapproximate the overall toricity and sagittal depth of the cornea to befitted. The rigid gas permeable portion may be optically clear with onlythe reduction in light transmission normally found in similarpolymerized materials. In one embodiment the rigid portion containscolorants and additives that narrow the band of light transmitted by thelens to reduce the chromatic aberration of the lens-eye system. Theanterior surface of the rigid portion may also have surface modificationto correct the total low and high order aberrations of the lens-eyesystem. Further, the surface profile of the anterior surface may bemodified to register the low and high order aberrations over the opticalsystem of the eye to account for the consistent natural displacement ofthe contact lens when applied to the eye. In addition, the surfaceprofile of the anterior surface may be modified to contain a multi-focalfeature for the correction of presbyopia. Also, the anterior surface ofthe lens may be treated to reduce the variance in the pre-lens tearfilm.

In another embodiment of the present invention, the substantially rigidcontact lens portion is joined to an outer soft hydrophilic portion byan intermediate adhesion enhancement zone. The adhesion enhancement zonemay contain a material that bonds to the substantially rigid portion andto the soft hydrophilic portion. The soft hydrophilic portion may have aposterior surface that is spherical, aspherical, toroidal orrotationally asymmetrical to approximate the overall or meridionalsagittal depth of the peripheral cornea, limbal region and sclera. Theanterior surface of the soft portion may be modified to produce athickness variation in the form of prism ballast or thin zones thatutilize lid interaction to produce a resultant rotational stability.

The soft section or skirt of the contact lens is designed to controlrotation by various methods. The methods include prism ballasting, thinzones, and rotationally asymmetrical contours that match the asymmetryof the cornea, limbus and sclera. In the preferred embodiment thesuperior portion of the lens is thinner than the inferior portion.

Methods of Manufacturing a Hybrid Contact Lens

Referring to FIGS. 1-5, one method of manufacturing a hybrid contactlens according to the present invention will now be described. Thismethod results in a fracture resistant product that is inexpensive tomanufacture.

Shown in FIG. 1, a rod 10 of rigid gas permeable material is cast havingthe desired characteristics. Upon the completion of the curing the rodis precision ground to produce a substantially uniform diameter. The rodis then machined by tool 15 into a primary blank 17 having an anteriordiameter 20 designed to conform to the collet of a computer numericallycontrolled lathe and a posterior diameter 25 designed to conform theoutermost diameter of the hydrophilic portion of the lens forpositioning in a tube, cup, or other containing device. The anteriordiameter 20 may range from 6 millimeters (mm) to 24 mm, and theposterior diameter 25 may range from 6 mm to 24 mm. In one embodiment,the anterior diameter 20 may be a separate material that is bonded orotherwise attached to the primary blank 17 for enduring the clampingforce of a lathe. The intermediate portion of the primary blank 17 issimultaneously machined to have a predetermined angle 30 for theinterface of the rigid and hydrophilic material in the finished lens.

One manufacturing method of the present invention has the posteriordiameter 25 substantially meet, or exceed, the hydrophilic sectionoutermost diameter 35, that is, the outermost diameter of the softsection of the contact lens, as shown in FIG. 4. In this embodiment, aboundary material 40 is then applied to produce a resultant wall, or cupto receive, and retain the hydrophilic liquid polymer. Alternatively,the primary blank 17 may be inserted into a cup, tube or othercontaining device to receive the hydrophilic material.

An alternative manufacturing method of the present invention includesthe application of an adhesion promoter to the primary blank 17,followed by the casting of the hydrophilic polymer into the liquidholding device formed by either the boundary material 40, tube, cup orother containing device.

In yet another embodiment, the primary lens blank 17 is mounted via theanterior diameter 20 in the collet of a computer numerically controlledlathe that is programmed to produce the aspherical posterior surfaceprofile in a manner that the profile does not require polishing, or mayonly need a light buff, or polish. The posterior surfaced button is thenmounted to a lens block wherein the axis of the block passes through thegeometric center of the lens 45, shown in FIG. 4.

The assembly with the posterior surfaced button is remounted in thecollet of a computer numerically controlled lathe, such as the Optoform80 with Variform attachment, or equivalent type that is capable ofproducing rotationally symmetrical or non-symmetrical surfaces to high,or quarter wavelength accuracy that preferably require a light buff, orno supplemental polishing (VARIFORM and OPTOFORM are trademarks ofPrecitech, Inc., of Keene, N.H.). It will be appreciated to thoseskilled in the art that other types of lathes may be employed. Thefinished lens is then removed from the lathe, with or without a lightbuff, deblocked and cleaned followed by. anterior lens surfacetreatment. Finally the lens undergoes hydration-extraction,sterilization and packaging.

Alternative manufacturing methods of the present invention may include:molding of the posterior surface and diamond turning of the moldedblank; contour cutting of the anterior surface of a posterior curvefinished blank; etching the anterior surface of a posterior curvefinished blank or predicate lens anterior surface; thin film depositionof a predicate lens anterior surface; and laser ablation of a predicatelens anterior surface.

Another manufacturing method may include molding or lathing a standardbase curve with a standard or semi-customized front surface, then usinga thermal or laser energy to modify the reflective index of the centermaterial to a desired optical requirement. This method replaces customlathing or molding expenses. Another method may include molding theposterior and anterior surfaces, and yet another embodiment may includea mechanical force or thermal molding manufacturing method.

Another method of manufacturing a hybrid contact lens according to thepresent invention is illustrated in FIG. 5. Step 1 shows a rod offluorosiloxane acrylate RGP material that will comprise thesubstantially rigid section of the hybrid contact lens. It will beappreciated to those skilled in the art that other types of materialsmay be employed. These other materials may include the followingmonomers, monomer mixtures, or their derivatives: trimeththyl-siloxyl;methyl-methacrylate; ethyl-methacrylate; ethylene glycoldi-methacrylate; octafluoro pentyl-methacrylate, tetra-methyldisiloxane,ethylene glycol di-methacrylate, pentafluoro phenylacrylate,2-(trimethylsiloxyl) methacrylate, bis(2-metharyloxyphenyl) propane,N-[2-(N,N-dimethylamino)ethyl], onethacrylate,N-[2-(n,n-dimethylamino)ethy], methacryalte, vinyl-pyrolidone,N,N-dimathacrylamide, acrylamine, hydroxyethyl methacrylate, siloxaneethylene glycol di-methacrylate, trifluoroethyl methacrylate,pentafluorostyrene, pentafluoropropyl methacrylate, unsaturatedpolyester; p-vinyl benzyl hexafluoroisopropyl ether, andsiloxanylalkylamide.

The rod, or button shown in Step 1 of FIG. 5, will preferably have a 5millimeter (mm) to 22 mm diameter and be 2 mm to 15 mm in length. In oneembodiment, the button may be bonded to another material for asubsequent operation, and as a possible cost saving. In Step 2, a plungetool is used to remove unnecessary hard material and allow a solidsection of material on one side for subsequent operations. Anothermethod may use the plunge tool to form the button assembly from Step 1,with a shape similar to FIG. 2.

In Step 3, a spacer is formed on the gripping side of the blank for thenext operation, or the blank can be bonded to a pre-form containingdevice to skip Step 4.

In Step 4, a tape, or other media that provides a retaining wall to holdthe soft material during polymerization is applied to the blank. In Step5, an adhesion promoter may be applied to the hard material and then thesoft material is poured inside the retaining wall, or other containingdevice, and allowed to cure. In Step 6, the spacer, or containingdevice, is removed and the blank is ready for subsequent manufacturingoperations.

Another method of manufacturing a hybrid contact lens according to thepresent invention comprises the use of a molded cup. In one embodiment,a pre-mold of a cup is created by using a bondable material that can bebonded by both hard and soft contact lens materials. This molded cup canbe either usable in the finished lens or removed during the castingprocess. A preferred embodiment molded cup will have an optimized angleto maximize the bonding strength between the hard and soft contact lensmaterials. In addition, the molded cup may have a special gripping areafor a subsequent lathing operation.

One method of manufacturing a molded cup of the present inventionincludes pouring a hard monomer to the open side of the cup and placingthe cup under a pre-programmed curing environment. The cup is thenplaced over a plastic container for containing a soft monomer fluid. Thesoft monomer fluid is then poured to the open side of the plasticcontainer and the assembly is placed under a pre-programmed curingenvironment. After the assembly is fully cured, it is ready to be lathedinto a finished hybrid contact lens.

Another method of manufacturing a hybrid contact lens according to thepresent invention comprises a molded base curve cup. In one embodiment,a base curve cup is molded to include a base curve surface and an edgeprofile on a pre-determined diameter, with a soft monomer retaining wallon one side, and a special gripping area for subsequent lathingoperations on the other side.

Yet another method of manufacturing a hybrid hard-soft contact lens ofthe present invention comprises using a molded base curve cup orfully-molded cup that has centering webs, or other indicators thatensure the device is centered. A pre-molded material separation cup isplaced on either the base curve side of the cup or the front surfaceside of the cup, preferably to achieve a centering of a meeting area, orjunction surface between the hard and soft contact lens materials.

Hard monomer is then poured in the center of the pre-molded materialseparation cup. The hard monomer will ultimately become thesubstantially rigid center second of the hybrid hard-soft contact lent.The assembly is then placed in a curing environment, and cured. Thensoft monomer is poured into the area between the hard core material andthe cup. The soft monomer is then cured, and then the assembly can belathed to form a finished hybrid hard-soft contact lens, or the assemblymay be molded so as to eliminate the need of subsequent lathing ormachining.

Alternatively, this process may be reversed so that soft monomer can bepoured into the outside of the material separation cup. The assembly isthen placed in a curing environment, and then cured. Then hard monomeris poured into the area between the soft material separation cup and thecup. The hard monomer is then cured, and then the assembly can be lathedto form a finished hybrid hard-soft contact lens or the assembly may bemolded so as to eliminate the need of subsequent lathing or machining.

Yet another molding method may be employed where both hard and softmonomer are poured together into a pre-mold cup, and then these twomonomers are cured together and subsequently machined, or alternatively,a hard-soft contact lens is directly formed without machining.

Referring to FIG. 6, methods of coupling the hard section of the contactlens to the soft section will now be described. Conventional hybridcontact lenses are generally not durable, in part because of the fragileconnection between the hard and soft sections of the lens. One featureof the present invention is that a variety of coupling configurationsare contemplated that securely couple the hard and soft sections of ahybrid contact lens.

One embodiment of the present invention employs an angled, or slopedsurface between the hard and soft contact lens sections, therebyincreasing the surface area, and thus the bonding force, or strengthbetween the two sections. Other embodiments use a variety of differentsurface features, or surface geometries that increase the durability andcomfort of a hybrid contact lens.

For example, the bonding angle 50, shown in FIG. 6, may vary from almost0 degrees to almost 90 degrees. That is, if a contact lens constructedaccording to the present invention was pressed against a flat surface,the angle defined by the interface between the hard and soft sections ofthe lens could vary from almost parallel to the flat surface to almostperpendicular to the flat surface.

In addition, the interface between the hard and soft sections of thecontact lens may include a variety of surface configurations, orgeometries 55. As shown in FIG. 6, these surface geometries 55 mayinclude ledges, protuberances, or substantially V- or W-shapedprojections. Other surface geometries 55 may include serrations,gradations, or any other shape that is not substantially straight, orplanar.

Referring now to FIG. 6A, a preferred hard-soft lens bonding method isillustrated. In this embodiment of the present invention, increasing thesurface area between the rigid and soft lens components increasesbonding strength between the two materials and minimizes lens breakage,or failure. Another advantage of this embodiment is that is provides asmooth transition between the rigid or hard, and soft materials. Thisproduces an exceptionally comfortable lens.

As shown in FIG. 6A, an interface, or junction 75 between the hard, orsubstantially rigid lens material 65, and the soft lens material 70 isillustrated. Also shown is angle “A” that may range between about 95degrees to about 170 degrees. In a preferred embodiment, angle A rangesbetween about 110 degrees to about 165 degrees. As illustrated, theinterface between the hard, or substantially rigid lens material 65, andthe soft lens material 70 is substantially V-shaped. Put differently,the interface comprises two intersecting planes that meet within thelens. This lens junction configuration provides a safety feature in theunlikely case of lens material separation during wear. Because of theV-shape, the edge of the hard lens material 65 is not “blade” shaped,and thus a sharp edge will not contact the cornea or eyelid, eliminatingthe risk of cuts, or abrasions.

The hard and soft sections of a contact lens constructed according tothe present invention may be joined, or coupled by a bonding material orresin comprised of the following monomer mixtures or their derivatives:vinylacetate; trifluoroethanol; methacrylate; ethanediamine;2-hydroxyethylmethacrylate (HEMA) and other esters of methacrylic acidformulated from acrylic bases; fluorine; silicone; fluorine/silicone;styrene and resultant polymers such as polystyrene; fluorine/styrene;and silicone/styrene.

The soft section of the contact lens constructed according to thepresent invention may be comprised of a variety of materials. Thesematerials may include the following monomer mixtures or theirderivatives: poly HEMA; hydroxyethyl acrylate; dihydroxypropylmethacrylate; polyethylaneglycol; acetoxysilane; trimethylesiloxy;ethyleneglycol-dimethacrylate; phenylethyl acrylate; and polyethyleneoxide. It will be appreciated to those skilled in the art that othertypes of materials may be employed.

Hybrid Contact Lens Surface Treatments

One feature of the present invention is that a variety of contact lenssurface treatments are contemplated. These surface treatments may beadded, for example, for the purpose of improving the comfort of the lensby means of improving the in-vivo wetting of the lens material. Anotherreason for using surface treatments is to create a uniform pre-lens tearfilm thickness. Variations in pre-lens tear film thickness induceaberrations while a uniform pre-lens tear film thickness allows theother aberration corrections to reach full effectiveness.

One embodiment of a hybrid contact lens constructed according to thepresent invention may include a surface treatment that provides uniformpre-lens tear film thickness between normal blinking action. Thesetreatments may comprise one or more of the following embodiments: 1)Plasma—the lens is placed in the presence of gases that are modified byoscillating electromagnetic energy. This creates a surface oxidationthat generate functional groups such as. OH or NH on the lens surface,which make the lens surface more wettable; 2) Ionic surfactants—polarmolecules are presented to the ionic lens surfaces with a resultantbonding of the molecules to the surface. An example is sodium dodecylsulfide. The 12-carbon chain combined with lauryl sulfonic acid providesa substrate that supports a more uniform tear film thickness; 3)Non-ionic surfactants—The lens may be exposed to non-ionic surfactantsthat provide a film on the lens. An example is an ethylene glycol chain;4) Soluble polymers—films of soluble polymers can be applied to therigid gas permeable material after manufacturing. Examples are TEFLONand HEMA. Other types of surface treatments are also contemplated.

Methods of Prescribing and Fitting a Hybrid Contact Lens

The present invention also contemplates methods of prescribing andfitting a hybrid contact lens. One method relates to non-rotating lensesfor correcting high order aberrations that include methods of placingthe coordinates of the aberration measurement over the coordinates ofthe pupil. Another comprises methods of placing a multifocal over thecoordinates of the pupil and customizing the design of the multifocalwith measurements of high order aberrations and pupil size.

One method of prescribing and fitting a hybrid contact lens employs aset of precision hybrid lenses with either spherical, aspherical ortoroidal posterior surfaces and spherical, aspherical or toroidalanterior surfaces. For a final monofocal lens, one embodiment contains aposterior aspherical surface and an anterior spherical surface. For afinal multifocal lens one embodiment contains a posterior asphericalsurface and an anterior aspherical surface.

One prescribing method of the present invention employs a centralregistration mark or marks concentric with the lens geometric centerthat are placed on either the anterior or posterior surfaces or withinthe matrix of either the rigid central portion, the intermediateadhesion enhancement zone or in the soft portion of a contact lens. Inthe preferred embodiment the rigid portion is at least 9 mm in diameterand a minimum of three marks are placed at a chord diameter of about 8mm. In the preferred embodiment the diameter of the overall lens isapproximately 14.0 mm.

A contact lens from the set with a posterior rigid surface thatapproximates the sagittal depth of the respective eye over the chorddiameter of the rigid portion is placed on the eye and allowed toequilibrate. The degree of rotational and translational movement isobserved. In the preferred embodiment the movement observed should beless than 5 degrees rotational and 0.3 mm translational. Upondetermination that the movement meets the required limit the residualhigh and low order aberrations are measured through the lens along withthe relative coordinates of the lens marks and the pupil margin, limbalmargin or other anatomical features. In the preferred embodiment aninstrument having the capability of detecting the lens marks and thepupil margin along with the residual high and low order aberrations isused.

An alternative embodiment of the present invention may includeinfrared-responsive marks, such as one or more registration marks, oneor more concentric marks, or other suitable marks, which emit or reflectinfrared light. For example, some types of wavefront aberrometers employinfrared light, which is generally in the form of a laser. Duringexamination of an eye fitted with a hybrid hard-soft contact lensconstructed according to the present invention, the infrared-reflectingmarks in the hybrid lens will be easily visible, enabling simultaneousevaluation of registration error, as well as aberrations. In oneembodiment, indocyan dye is employed, but it will be appreciated thatother dyes, powders, or other types of infrared-responsive products maybe employed.

Another method of prescribing and fitting a hybrid contact lens employsa set of precision rotating and non rotating hybrid contact lenseshaving known ocular surface profiles, optical corrections and thicknessprofiles. In one embodiment, the lenses contain circumferential marks inthe mid periphery. A lens is selected and applied to the eye and allowedto equilibrate. The coordinates of the marks and the pupil aredetermined. The aberrations of the lens-eye system are measured. Amathematical model provides analysis of the known thickness profile, theregistration error of the coordinates of the lens and the pupil, and theresidual lens-eye aberrations to derive the computer numericallycontrolled lathe files for diamond turning a resultant thickness profilefor a final contact lens having the same ocular surface profile.

For example, one prescribing and fitting method of the present inventionmay include the steps of: selecting the initial lens to conform to theshape of the underlying cornea; capturing an image of thecircumferential marks and the pupil margin; measuring the residual lowand high order aberrations of the lens-eye system; performing analysisutilizing the known ocular surface profile of the lens, the initial lensthickness profile, the registration error, and the residual lens-eyeaberration error to determine the resultant files for generating a finalcontact lens.

Another method of prescribing and fitting a hybrid contact lens employsa set of contact lenses having a known central zone ocular surfacegeometry, thickness, anterior surface geometry and diameter. Thepreferred residual lens eye aberration correction and coordinatedisparity are determined by clinical measurement, and the thicknessprofile variation is derived by computer modeling, or other methods, inorder to specify a superiorly performing lens.

Yet another method of prescribing and fitting a hybrid contact lensemploys a set of contact lenses with fixed ocular surface geometries,overall diameters and front surface geometries, over which clinicalmeasurements are made from which the final prescription parameters arederived by computation, or other methods.

Another method of the present invention comprises correcting visualacuity deficiencies in presbyopia by reduction of the residual lens-eyeaberrations. The method uses a set of hybrid contact lenses having aknown ocular surface profile and thickness profile and containingcircumferential marks for the purpose of registration of the finaloptical correction with the 5 coordinates of the optical system of theeye. The method steps may include: selecting the initial lens to conformto the shape of the underlying cornea; capturing an image of thecircumferential marks and the pupil margin; measuring the size of thepupil in photopic, mesopic and/or scotopic illumination; measuring theresidual low and high order aberrations of the lens-eye system; andperforming analysis utilizing the known ocular surface profile, theinitial lens thickness profile, the registration error, the pupil sizeand the residual lens-eye aberration error to determine prescriptioninformation for generating a final contact lens. In one embodiment ofthis method, the diameter of the near focused optical correction may bein the range of about 1.8 mm to about 4.0 mm.

Another method of the present invention employs a multifocal contactlens and corrects visual acuity deficiencies in presbyopia by reductionof the residual lens-eye aberrations. The method uses a set ofmultifocal hybrid contact lenses having a known ocular surface profileand thickness profile and containing circumferential marks for thepurpose of registration of the final optical correction with thecoordinates of the optical system of the eye. The method steps mayinclude: selecting the initial lens to conform to the shape of theunderlying cornea having a multifocal anterior surface; capturing animage of the circumferential marks and the pupil margin; measuring thesize of the pupil in photopic, mesopic and/or scotopic illumination;measuring the residual low and high order aberrations of the lens-eyesystem; and performing analysis utilizing the known ocular surfaceprofile, the initial lens thickness profile, the registration error, thepupil size and the residual lens-eye aberration error to determineprescription information for generating a final multifocal contact lens.In one embodiment of this method, the diameter of the near focusedoptical correction may be in the range of about 1.8 mm to about 4.0 mm.

Another method of the present invention employs a multifocal contactlens and corrects visual acuity deficiencies in presbyopia by reductionof the residual lens-eye aberrations. This method also incorporatesinformation relating to a light transmittance pattern. The method uses aset of multifocal hybrid contact lenses having a known ocular surfaceprofile and thickness profile, light transmittance pattern, andcontaining circumferential marks for the purpose of registration of thefinal optical correction with the coordinates of the optical system ofthe eye. The method steps may include: selecting the initial lens toconform to the shape of the underlying cornea having a multifocalanterior surface; capturing an image of the circumferential marks andthe pupil margin; measuring the size of the pupil in photopic, mesopicand/or scotopic illumination; measuring the residual low and high orderaberrations of the lens-eye system; and performing analysis utilizingthe known ocular surface profile, the initial lens thickness profile,the registration error, the light transmittance pattern, the pupil sizeand the residual lens-eye aberration error to determine prescriptioninformation for generating a final multifocal contact lens. In oneembodiment of this method, the diameter of the near focused opticalcorrection may be in the range of about 1.8 mm to about 4.0 mm.

The above-described methods of prescribing and/or fitting a hybridcontact lens may also employ additional method steps or additionaldevices. For example: the method of determining the difference in thecoordinates of the center of the circumferential lens marks and thepupil margin may incorporate a reticle of a biomicroscope or a camerawith subsequent manual or electronic digital image detection. Inaddition, the method of measuring the residual aberrations of thelens-eye system may incorporate Shack-Hartmann aberrometry, aberrometersutilizing Tscherning technology, laser ray-tracing or Talbotinterferometry technology.

Correction for Various Components of the Visible Light Spectrum

Aberrometry performed with the contact lens in place provides us withknowledge of the angles that the rays emerging from the anterior lensmake with respect to the visual axis. In the perfect case, the rayswould all emerge parallel to the visual axis. But as illustrated in FIG.7, in the presence of aberrations these rays make an angle with respectto the visual axis and this angle is not restricted to the plane of thepaper. To correct these aberrations, there are generally two variablesto play with. The first variable is the slope of the contact lens at thepoint each ray emerges from the contact lens. Changing this slope willchange the direction of the ray exiting the eye via Snell's Law. Therewill exist a slope of the anterior contact lens surface that causes theray to exit parallel to the visual axis. The second variable is thelocal lens thickness at the point where each ray exits the contact lens.As this thickness is adjusted, the- slope of the surface at this pointalso needs to change in order to keep the emerging ray parallel to thevisual axis. There will exist a set of local thicknesses and slopes thatsimultaneously cause all of the emerging rays to be parallel to thevisual axis and keep the overall thickness of the lens reasonable, thatis, not too thin or too thick.

Aberrometry is normally only performed at one wavelength, usually in theinfrared. However, as illustrated in FIG. 8, the slopes of the variousrays will depend on the color of the light. In general, blue lights rayswill be more convergent than the green light rays. The red light rayswill be more divergent than the green light rays.

The dilemma now is which color rays should be made parallel to thevisual axis. If the eye responded equally to all colors in the visiblerange (wavelengths of about 380 nanometers (nm) to about 780 nm), youwould make the rays that corresponded to the middle wavelength parallelto the visual axis. In this manner, half of the light would be divergingand half of the light would be converging as it left the eye.

Referring to FIG. 9, for a uniform response, the center wavelength ofthe visible spectrum would be ideal for correcting aberrations since,the equal areas of the rectangles on either side of this wavelengthmeans equal amounts of energy is distributed around this wavelength.

However, the eye does not respond to all wavelengths the same. Thephotopic response curve, illustrated in FIG. 10, shows that the eye ismore sensitive to the red/green end of the spectrum. The same sort ofconcept as described above can now be used to determine the idealwavelength for correcting aberrations. The ideal wavelength gives equalareas under the photopic response curve on either side, as shown in FIG.10.

In addition to the variation in response of the eye to different colors,the present invention may also vary the transmission of the contact lensto different colors. This may be beneficial to reducing the effects ofchromatic aberration in the eye. If the contact lens transmission ismultiplied by the photopic response of the eye, a net response of theeye results, as illustrated in FIG. 11. One ideal wavelength is based onthis net response which again gives equal areas under the curve. Thisideal wavelength is then used as the target for correcting aberrationsby the means described above.

For example, for either a final monofocal or multifocal lens, oneembodiment hybrid contact lens constructed according to the presentinvention contains colorants that reduce the transmission at both theblue and red end of the visible spectrum thereby narrowing the band oftransmitted light and potentially shifting the peak of the transmissioncurve of the lens. A contact lens of the present invention may thereforeinclude color additives for the purpose of reducing light transmission,or color additives for the purpose of reducing chromatic aberration.

Thus, it is seen that a hybrid hard-soft contact lens system, method,and article of manufacture is provided. One skilled in the art willappreciate that the present invention can be practiced by other than theabove-described embodiments, which are presented in this description forpurposes of illustration and not of limitation. The description andexamples set forth in this specification and associated drawings onlyset forth preferred embodiment(s) of the present invention. Thespecification and drawings are not intended to limit the exclusionaryscope of this patent document. It is noted that various equivalents forthe particular embodiments discussed in this description may practicethe invention as well.

1-43. (canceled)
 44. A method of prescribing a hybrid contact lens, the method comprising the steps of: providing a contact lens that approximates a shape of an eye; placing the contact lens on the eye; determining a direction of a light ray exiting the contact lens; and adjusting the contact lens so that the light ray exists the contact lens substantially parallel to a visual axis.
 45. The method of claim 44, wherein the step of adjusting the contact lens so that the light ray exits the contact lens substantially parallel to the visual axis comprises the steps of: adjusting a slope of the contact lens; or adjusting a thickness of the contact lens.
 46. The method of claim 44, wherein the contact lens is adjusted to provide a visual light spectrum wavelength that has substantially equal areas under a photopic response curve.
 47. The method of claim 44, wherein the contact lens is adjusted by the steps of: multiplying a contact lens light transmission characteristic by a photopic eye response so that the visible light exiting the contact lens has substantially equal areas under a photopic response curve. 